Four excited states, A(2)A ", B(2)A', C(2)A', and D(2)A " of the acetyl radical CH(3)CO, which is the intermediate of the Norrish type I photolysis reaction of acetone, were found by MR(SD)CI calculations. Their vertical excitation energy from the ground state X(2)A' is 60.0, 113.0, 154.5 and 161.4 kcal/mol, respectively. The A(2)A " state is a bound state while the X(2)4' state has a low dissociative energy barrier to form CH(3) and CO. Based on these calculations, a state-specific reaction path of one photon and two photon photodissociation of acetone is described. (C) 1998 Elsevier Science B.V.